<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <!-- 双飞翼布局 -->
  <div id="hd">hd</div>
  <div id="middle">
    <div id="inside">3123</div>
  </div>
  <div id="left">left</div>
  <div id="right">right</div>
  <div id="footer">footer</div>
</body>
</html>
<style>
  #hd{
    height: 50px;
    background-color: #666;
    text-align: center;
  }
  #middle{
    float: left;
    width: 100%;/*左栏上去到第一行*/
    height: 100px;
    background: blue;
  }
  #left{
    float: left;
    width: 180px;
    height: 180px;
    margin-left: -100%;
    background-color: green;
  }
  #right{
    float: left;
    width: 200px;
    height: 180px;
    margin-left: -200px;
    background-color: green;
  }
  #inside{
    margin: 0 200px 180px;
  }
  #footer{
    clear: both;
    height: 50px;
    background-color: #666;
    text-align: left;
  }
</style>